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I'm a well-known mainframe performance guy, with almost 30 years of experience helping customers manage systems. I also dabble in lots of other technology. I've sought to widen the Performance role, incorporating aspects of infrastructural architecture.
I'm a world-famous podcaster and screencaster (albeit VERY thinly spread). :-)

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Seasoned readers will recognise the title of this post as a bad pun, rather than a mis-spelling. [1] One emergent theme in our code for Parallel Sysplex Performance is treating individual coupling facility structures on their merits.
For example, lock structures are different from cache structures. But there is much commonality in the instrumentation.
For example Maximum Size, Size and Minimum... [More]

I have to admit to being a bit of a wannabe when it comes to automation. Certainly most of my career has been built on using and building tools - and you’d have to pry them out of my luke-warm retired hands. But when it comes to automation in my personal life it’s a bit of a different story: I haven’t (yet) got into Home Automation. Baby steps still. 1 I don’t use many... [More]

I’ve been musing on counting transactions for a customer recently.
I’d like to share some of that thinking with you. This post is about RMF SMF Type 72 data, rather than middleware-specific stuff.
That’s because it’s Generic - applicable to multiple transaction managers. Much lighter weight - so every customer can collect, retain indefinitely, and process it. I’m... [More]

Getting back “in the studio” was really nice. And we never had any doubt we’d keep recording - so the title is very tongue in cheek. Below are the show notes. The series is here . Episode 7 is here . Episode 7 “We Were On A Break” Show Notes Here are the show notes for Episode 7 “We Were On a Break”. The show is called “We Were On a Break”... [More]

When looking at a batch job 1 I like to see how the data flows through the various steps. The first step - some 23 years ago - was to look at the Life Of A Data Set (“LOADS” for short). 2 With LOADS - for VSAM and non-VSAM data sets - you can see who reads and writes the data set. You can also see the EXCP count. More on that in a bit but suffice it to say EXCP count might be enough to... [More]

The title of this post is a Physics reference but this is not about Physics. 1 A customer asked me the question “why am I not getting balanced CPU Utilisation between the various machines”? I’m responding without data at this stage so I’m going to be even more “hand wavy” than usual - both in the long call I had with them and this post. So, let’s take it... [More]

This is a post where I have, yet again, to be careful to obfuscate the customer’s situation; I’ve no wish to embarrass them.
So you’ll forgive me if there are no numbers.
But there is a lesson worth sharing here.
So I’m going for it… It’s about DB2 and Workload Manager. 1 I was recently asked to explain why an application’s DB2 Accounting Trace was... [More]

(Reposted without change as I accidentally deleted it while getting rid of a SPAM comment.) Episode 5 had a different feel for me.
It was our first “trip report” episode, and it felt much looser for that. In fact the sound effects between topics could’ve been elided but for now I’m sticking slavishly to the format.
It didn’t feel too artificial to me. I’m... [More]

Episode 6 was a complete surprise to us! Marna had thought I was on vacation a week earlier than I was. To be fair, I expected to be with a customer in Australia that week. But then the workshop got pushed back and so this week came free [1] So we went “why not?” and so this episode was born. It is of course largely built around this blog post but we had a couple of other things we... [More]

Or “ The Man Who Knew Too Little ”? This post is occasioned by a number of things coming together, the most recent of which is reviewing a very nice upcoming RedPaper. The gist is this:
You’re responsible for managing Performance, Capacity and (to some extent) mainframe costs.
But you can’t rely on anybody to tell you anything. A bit pessimistic, perhaps a little... [More]

Pardon the bad pun. Perhaps I should’ve written “Engine-ering” but where exactly do you put the dash? [1] There were hints on this topic in Born With A Measuring Spoon In Its Mouth but the real motivation came from a z196 customer without Hiperdispatch enabled. But what on earth am I on about? OK, here we go: Generally our [2] code doesn’t report down to the single engine... [More]

SMT really was born with a measuring spoon in its mouth. [1] Let me rewind a few years… So, when SMT (Simultaneous Multithreading) was being designed I was privileged to be on the periphery of discussions about how to instrument SMT.
Things like CPU Utilisation get a little wierd in the SMT case, as you can imagine. Now, I was only on the periphery of the discussions and they carried on... [More]

Episode 4 was, of course, our fifth podcast episode. I had a lot of fun making the intro - with Audacity.
I’m not sure if it’s “lost souls” or “tuning in”.
It was meant to be the latter but the former is also good. Below are the show notes. The series is here . Episode 4 is here . Episode 4 “The Road To Munich” Show Notes Here are the show notes... [More]

You probably don’t have the same problem I do, namely not having access to SMF data from all the systems in your mainframe estate. You’ll recognise that as a provocative statement if ever there was one;
For all sorts of reasons not every system’s RMF SMF is collected. Most notably, test systems often aren’t instrumented. This post is about Coupling Facility (CF) image... [More]

On Twitter I joked ‘refactoring’ is ‘taking perfectly well working code and risking breaking it’.
This post describes one such exercise. tl;dr: It was well worth it! In DFSORT Tables I wrote about a technique to create tables (or grids) using IFTHEN. It’s been a maintenance headache to the extent that the “Principle” Of Sufficient Disgust kicked in.
So... [More]

As I’ve indicated elsewhere we use iThoughts for outlining our podcast episodes (and use it to track completion). I’ve developed quite a nice technique for iThoughtsX (the macOS flavour), which I’ll share with you. This is in case you’re inclined to play with newer toys. Consider the following fragment of an outline: You’ll see some of the nodes are filled (arguably)... [More]

Already this year I’ve posted thrice on DDF: DB2 DDF Transaction Rates Without Tears DDF Batch DDF Counts It’s clearly something that’s important to me right now. So this post is to mention I’m putting the finishing touches to a new presentation (the third of the year so far). I’m giving it to European customers in Munich in mid June. I’m also giving it as an... [More]

You probably wonder why I post to my blog echoing our podcast episodes. There are two reasons: Yes, it alerts more people to our podcast series. Well duh. It gives me a chance to inject something more personal about the episode. So in the latter spirit I’d say the highlight for me of making Episode 3 was getting the “three part disharmony” working. Glenn Wilcock very kindly... [More]

Some of my blog posts revolve around a single SMF field, or maybe a couple. This post is one of those. If I look at my customers’ mainframe estates [1] , especially the DB2 portion of them, they’re getting more complex by the year. In particular, quite a few customers are in the “tens of DB2 subsystems” category. One of the things driving the number up are SAP... [More]

In
Episode 1 of MPT Podcast we discussed Markdown and Marna asked me if it could be run on z/OS.
My answer was “you could try a Python Markdown processor via Jython ”. [1] Then, on IBM-MAIN, Dave Griffiths suggested using one of the Java Markdown processors, instead of Jython. So I got to experimenting: I downloaded Java Markdown to my Linux machine. It’s a jar file. I wrote a... [More]

I think we were much more relaxed when we put this episode together, and I hope it shows. We’re learning our craft, and I think quite fast. Below are the show notes. The series is here . Episode 2 is here . Episode 2 “Sound Affects” Show Notes Here are the show notes for Episode 2 “Sound Affects”. Follow Up We had some follow up items: Marna talked about the new SDSF... [More]

We enjoyed recording Episode 0, learning as we went. And people seem to have enjoyed it. So we recorded another one. So here are the show notes for Episode 1. By the way we publish the show notes with the audio. You can get the series (and it is a series now) from here , and Episode 1 from here . And rest assured we have plenty of plans for the future. Episode 1 “A Luta... [More]

I’m delighted Marna Walle and I are collaborating on a podcast series. We’re calling it “Mainframe, Performance, Topics Podcast”. You can guess where we got the name from. Below are the show notes. The series is here . Episode 0 is here . Episode 0 “Sic Parvis Magna” ( “Greatness From Small Beginnings" ) Show Notes Here are the show notes for Episode... [More]

Here are are two questions people would like easy answers to: What are the big CPU DB2 jobs accessing this DB2 subsystem? Which job steps access MQ? This post shows you how to answer both these questions without DB2- or MQ-specific instrumentation . The “without DB2- or MQ-specific instrumentation” phrase is important:
I’m working with a customer with something like 50 DB2... [More]

One of my new 2016 presentations is called “How To Be A Better Performance Specialist” - though I really could use a snappier title. Here’s the abstract: I’ve spent 30 years doing Performance and Capacity. You’d think it’d seem stale and repetitive by now. Not a bit of it. It’s still fresh and interesting. More to the point I think I’m... [More]

I wish I’d started counting DB2 subsystems before. A recent study saw 43 DB2 subsystems, in 13 Data Sharing groups (and a few in none), across a large number of z/OS systems. And if I try to remember other studies these numbers have been typical of them (but this is not a typical set of numbers). Two thoughts entered my head: How on earth do you get to these sorts of numbers, and is it a... [More]

DDF and Batch sound like two opposite ends of the spectrum, don’t they? Well, it turns out they’re not. I said in DDF Counts I might well have more to say about DDF. I was right. I’ve known for a long time that some DDF work can come in from other z/OS DB2 subsystems, but not really thought much about it. Until now. And I don’t really know why now. Maybe it’s just... [More]

I don’t think I’ve ever written very much about DDF.
Now seems like a good time to start. I say this because I’ve been working pretty intensively over the last couple of weeks on upgrading our DDF Analysis code.
Hence the recent DFSORT post ( DFSORT Tables ). I’m actually not the DB2 specialist in the team but, I’d claim, I know more about DB2 than many people who... [More]

It’s been a while since I posted a DFSORT trick - and it’s high time I did. This post follows (distantly) on from
More Maintainable DFSORT and is occasioned by some recent development work on our tools. As so often happens, developing this code has been a bit of a journey of discovery.
And I’ve learnt (the hard way) a couple more ways you can make the code more maintainable.... [More]

I can cope with both “zee” and “zed”. [1] I love the myriad ways of pronouncing “CICS”. I can even detect such things as “Day Bay Tway” when I hear them. But there are a couple of things that I’m slightly bemused by: People saying “zee-oss” or “zed-oss” or “zoss”. People calling WLM “Willem”. I... [More]

WLM will give up on an unachievable goal, eventually. Recently I came across a customer who didn’t know this and for whom this was a big problem. [1] This customer, like many others, was running heavily constrained for CPU. [2] But it does have consequences. In this particular case they had defined two service classes - one for their main Production IMS address spaces and one for their... [More]

After writing Reviewing The Situation I got thinking. [1] I’ve known for a long time the WLM Policy (XML) has timestamps in it. The thought was “maybe there’s value in doing timestamp analysis”. Here is a fragment of a real customer policy, showing a resource group definition: It’s pretty easy to read. Obviously the XML elements whose node name start with... [More]

I’ve been very lucky (and kept busy and challenged) these last two months. In addition to my usual case load of customer situations I’ve had the enormous privilege of participating in the ITSO 2015 Mainframe Topics tour.
I’ve presented whole-day sessions on Performance and Availability in five cities:
Amsterdam, Paris, Warsaw, Vienna and Bromsgrove. [1] The main topics have... [More]

It’s very early days for Twitter Polls but I think they have promise. So here’s a post on my experience with them in their infancy. [1] The point of writing about it is twofold: To encourage others to try it - both as a pollster and as a respondent [2] . To encourage Twitter to tweak it a bit. I’m always looking for ways to interact with people. As you probably know Twitter is... [More]

In IRD And Hiperdispatch - Wrong ’Em Boyo I briefly mentioned the concepts of Parking and Unparking. It wasn’t appropriate to cover them in depth there. So I’ll talk about them now, focusing on the RMF instrumentation. But first a brief discussion on Parking versus IRD Logical Processor Management. IRD could - without Hiperdispatch - vary logical processors on and offline. [1]... [More]

Applying the maxim “the customer is always right” this week revealed a bug in my analysis code.
It also gave me the opportunity to write about how RMF sees the interaction between IRD Weight Management and Hiperdispatch. [1] But let me start with some brief, basic information about the technologies in question.
If only this proves useful the blog post will still have been worthwhile.... [More]

Sometimes a little visual tweak can make all the difference.
This post is about one such case. Actually the code change to achieve it was quite complex but the visual rearrangement is simple. I have a number of customers with Integrated Coupling Facility (ICF) processor pools with both dedicated and shared Coupling Facility (CF) processors. For Production most people (sensibly) define their ICF... [More]

It's that time of year when I start to think about writing conference presentations for user groups and conferences in 2016.
Already I have three in mind, with varying degrees of sketchiness.
Their working titles are: He Picks On CICS Fun With DDF So You Want To Be A Better Performance Specialist? I don't want to “design by committee ” and as for focus groups yeugh! But I... [More]

Or can they? Actually I can’t answer that question.
I’m aware my blog gets distributed in Development in Poughkeepsie (at very least) so maybe one of them can give a far better answer than I can. Though this post isn’t meant to address this in its entirety I have a point of view: A long time ago I learnt there were processor-related control blocks in 24-Bit Virtual. Though in... [More]

This is about the third time I’ve written about this, and it probably won’t be the last. [1] I was presenting to customers about the Coupling Facility Path Latency statistics I’ve previously spoken of when one of them told me of the following incident.
I’m sure he won’t mind me sharing it without you, so long as I don’t identify the source. The customer has two... [More]

It’s difficult to write about a live situation for two reasons: You don’t want to spoil the surprise. You mustn’t expose the customer. Actually, make that three reasons: You don’t know how it’s actually going to turn out. So why am I writing at all? Well, the big engagement my team are involved in exemplifies the method for tuning CPU down, with a twist or two of its... [More]

I’ve played some more since I wrote Slide Over A Bit , most notably from the perspective of developing a web app that acts as a Slide View widget. This post addresses some of the issues. In particular: Offline web apps, a feature of HTML 5. Responsive design - writing a web app that works well in Slide View mode while still looking OK in Full Screen mode. Remote hosting. I wrote a better... [More]

The last post hit both the “Mainframe” and “Performance” aspects of this blog.
This one is firmly in the “Topics” category. [1] You might’ve noticed a slew of announcements from Apple recently, and iOS 9 and OS X 10.11 “El Capitan” delivery. [2] I’d like to talk here about one feature of iOS 9 that is more useful than it appears at first... [More]

DB2 Accounting Trace names are a(n endless) [1] source of fascination to me. As many of you know, bridging the gap between DB2 and callers and the environment is permanently an imperative for me. These names might be cryptic but they can usually be related to non-DB2 concepts. As I’m about to explain this to colleagues at work I thought I might as well explain it to the world (or at least my... [More]

In What’s The Latency, Kenneth? I talked about Coupling Facility Link distance and OA37826.
The whole supposition was that you might want to know about really long links. A recent situation showed me that short distances might be a different and interesting matter. So what’s a microsecond or two amongst friends? Well, 1μs represents 100m of distance and 2μs represents 200m.
This is,... [More]

In true IBM fashion this post features graphs without scales. [1] My aim is to share a rhetorical device I used in a recent customer workshop.
I hope you find it useful. [2] The customer was worried about a piece of hardware whose responsiveness had deteriorated over the past year, but got better in recent days, coinciding with some tuning changes they’d made.
This graph shows that:... [More]

Numbers are key to what I do;
They’re the basic data I use as evidence.
Without them it’s often just supposition. And nowhere is this truer than when trying to reduce bad [1] habits and reinforce good ones. So a while back I invested a small amount of money in a very nice little app:
Tally, a Simple, Eyes-Free Counter for iOS . So this post is about why I like this app and also a... [More]

Editorial Preview As a matter of chance, over the past few months I've been involved in a number of situations where IMS has been an important component of the customers' infrastructure (and I'm about to be involved in another one). Although I hope my customers don't think I think of them only as test data it's been good to have their data move my story forward:
Several nice... [More]

As most people know, I thoroughly enjoy conferences and learn a lot.
The Dublin one 18 - 22 May was no exception. It was great to meet up with old friends, connect with potential new ones and have a couple of compromising photos of myself and friends to prove it. But you probably don’t care much about that - unless you’re in those photos. So here are the slides from the three... [More]

I’ve put off writing this post for a while.
Largely because it might sound like boasting.
The truth being I have very little to boast about. But here goes anyway. I’m a fitful [1] exerciser.
It’s not that it’s painful but that it’s not interesting.
I’ve never found a sport I enjoyed watching nor partaking in. But with that characteristic it’s been a... [More]

Just a brief one this time.
A customer recently asked me how to detect Sysplexes sharing Infiniband links. [1] It arose when discussing the information in the new(ish) Channel Path Data Section in RMF’s SMF 74 Subtype 4 record. The question really boils down to “how do I detect in RMF / SMF different Sysplexes using the same identifiable link”?
[2] My first suggestion was the... [More]

This post is one where I really don’t speak for IBM. [1] It’s also one that’s firmly in the “Topics” category of “Mainframe, Performance, Topics”, [2] being about the emergent fields of iOS Automation (and Web Automation). And, while I give Remember The Milk a “could try harder” score I’m actually a big fan of what they do.
Like many... [More]

Being about Coupling Facility structures, maybe this should be called “re Structuring”. Standing on the shoulders of giants, as I do , it is with some temerity that I rethink one of their designs.
And it’s only because you might find it helpful that I mention it now. Since the dawn of time coupling facilities have contained four kinds of structures: Lock Cache List Serialized... [More]

Regular readers of this post will have noticed the masthead
[1] changing. I thought it appropriate to replace the zEC12 (and zBX) graphic with the new z13.
I’ve also taken the opportunity to weave in a little gag.
The blog’s title remains “Mainframe Performance Topics” but you’ll see I’ve injected a couple of commas in the masthead. These commas make all the... [More]

It’s more like someone rich lighting their cigar with a hundred dollar bill. Seriously, this post is about Coupling Facility Lock Structure False Contention and why it matters.
It is, of course, inspired by a recent customer situation. Before I explain what False Contention is, and then go on to talk about its impact and instrumentation, let me justify the title by asserting
Lock... [More]

As you know, we turn data into reports and try to make sense of it.
One thing we’ve not done before is use colour in our textual and tabular reports.
So here’s what I’ve learnt about how to make B2H use colour.
Our Reporting Process But first a word or two about how we get these reports. We collect SMF data into engagement-specific VSAM-based performance databases. We use... [More]

OA37826 really is the gift that keeps on giving: I got really nosy about Coupling Facility links when it came out [1] , though most customers didn’t get the added benefits of CFLEVEL 18 for a while. This post is about a customer installation which pointed out another benefit of the instrumentation.
[2] Customer Example I’ve simplified the customer situation a little - in a way that... [More]

… or probably more. I was going to use “Send In The Clones” but I’ve already used it - and someone who shall remain nameless once misremembered it as “Let There Be Clones”. Let there be clones, indeed. So, how do I detect cloned CICS regions, for example? (And if you want to know why I’m asking that question now it’s an enforced rereading of
CICS... [More]

In He Picks On CICS I mentioned XCF traffic and CICS. This post is about a customer situation where looking at this traffic was important. Often I’m looking for topology (maybe “tourist information” to some of you). This time I have another motivation: Performance. In this customer saving z/OS CPU is important. [1] I’ve noticed that the Coupling Facility CPU has XCF... [More]

As I’m working with a couple of colleagues on a performance study I thought I’d list some “starter set” questions I’d ask about any customer’s WLM policy. [1] Before you go too far with this post you might like to read
Analysing A WLM Policy - Part 1 and
Analysing A WLM Policy - Part 2 but I don’t think I’m repeating myself much here. So here are... [More]

It’s a little surprising to me that nobody complained about one aspect of the behaviour in the code in
GreaseMonkey Script To Sum Selected Numbers In A Web Page .
I’ve been muttering under my breath and I wrote the code. This code naively assumes that in every web page there is just one body element.
It is rather naive, and I’ve known that for a long time. What really... [More]

This post is meant to inspire people who like programming the web to do simple tasks.
It contains a sample Firefox GreaseMonkey [1] script, which I hope you will find useful. [2] Suppose you are looking at a web page, perhaps one with a table in, and you want to add up some numbers you see there.
Perhaps they’re in a column in that table. With this script you select the numbers... [More]

Here's an interesting case that illustrates the effect of distance between a z/OS image and a Coupling Facility structure. I don't think this will embarrass the customer;
It's not untypical of what I see.
If anything I'm the one that should be slightly embarrassed, as you'll see... A customer has two machines, 3 kilometers apart, with an ICF in each machine and Parallel Sysplex members in each... [More]

In After A Decent Interval I talked about the need for frequently-cut SMF Interval records.
This post is about bad behaviours (or maybe not so bad, depending on your point of view). It’s actually an exploration of when interval-related records get cut, which turned into a bit of a “Think Friday” experiment.
But I think - quite apart from the interest - it has some usefulness in... [More]

At UK GSE Annual Conference I presented on DB2 and Workload Manager.
It occurred to me that one of the slides was a good basis for a blog post, posing the question “what’s the point of WLM?”
And this was the slide, with me “for scale purposes”. (Thanks to Karen Wilkins for the photograph.) So let me try to give you a synopsis of my view, expanding on each of the... [More]

If you come to my blog only for Performance- or SMF-related topics you’re going to be disappointed in this post.
But if, like me, you’re interested in storytelling and web-related technologies then read on. This post is about HTML5 Canvas - a technology I really like. Some Of Why I Care About Web Technologies To try and keep this focused I’m going to talk only about why web... [More]

… and other address spaces, too. In Once Upon A Restart I talked about how to detect IPLs and restarts of CICS regions and MQ subsystems (and other long-running address spaces) - from SMF Type 30 Interval records. It’s easy to see starts but what about stops ? [1] It turns out you can estimate when address spaces stop from the SMF 30 Interval records (Subtypes 2 and 3): When there is... [More]

As you’ve probably gathered I like to get nosy about how customers run systems.
This is probably best and most recently exemplified by this blog post:
Once Upon A Restart So this post is about another piece of curiosity:
What spikes can tell us about how people run systems.
In a way it’s similar to what restarts tell us, hence the above blog post link. I like “Think... [More]

Back in 2010 I wrote about a graph I’d developed for understanding how a Service Class Period’s velocity behaves. That post is here: WLM Velocity - “Rhetorical Devices Are Us” . At the time I was concerned not to show up the customer by displaying the graph. I think that was the right decision. But in the presentation I mention here: Workload Manager And DB2 Presentation... [More]

Some technologies show up “in the field” very soon after they’re announced and shipped. Others take a little longer. Back in 2009 [1] I blogged about one technology - DFSORT JOINKEYS. For this post to make much sense you’ll probably want to read that post first. Here it is: DFSORT Does JOIN . Dave Betten and I have - at last - a set of data from a customer where one of the... [More]

I’m pleased to be presenting three sessions at UK GSE Annual Conference, Tuesday 4th and Wednesday 5th November in Whittlebury Hall. Two are on the zCMPA (Performance and Capacity or “UKCMG”) track: Life and Times of an Address Space (Tuesday) zIIP Capacity Planning (Wednesday) I’ve written about these extensively.
Obviously they’re evolved a bit and I have specific... [More]

Sitting in Dave Gorman’s Broker V9 presentation in Budapest it struck me it would be a useful exercise to apply the “Systems Investigation” techniques I write about to Broker running on z/OS. So let’s see how far we can get with SMF 30 Interval records, in the vein of Life And Times Of An Address Space . It’s a nice exercise [1] but I think it’s directly useful... [More]

In Budapest at the European System z Technical University I presented three topics: zIIP Capacity Planning (twice) Life And Times Of An Address Space Parallel Batch Performance Considerations The links take you to the Slideshare uploads of these presentations. The first two of these are updated for this conference and I’ve overwritten the previous versions - as the new versions subtracting... [More]

“Mobile” appears to be “flavour of the month” right now, and this week at System z Technical University it has certainly been a topic in evidence, whether it’s discussions in the breaks, sessions on software pricing, or sessions on Mobile-enabling technology. I don’t intend in this post to discuss any of these. Instead I want to talk about the types of users... [More]

You can blame the weather for this post. I’m writing it on a flight above thick cloud [1] on my way to Munich and then to Budapest for this year’s European System z Technical University. I like to see the complete picture when I’m examining systems:
It makes getting it right so much easier.
And there’s something rather satisfying about getting your arms all the way round... [More]

Sometimes I’m in the mood to carefully peck at the text and sometimes I’m in the mood to just “splurge write”.
And sometimes a bit of both. This post is a case in point:
I just want to get the words out as fast as I can. Now, I do quite a bit of writing on iOS as it lets me write wherever and whenever I get the chance.
I like its prediction and correction... [More]

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If you have a large mainframe estate it can be difficult to keep track of when the various moving parts start and stop.
For example, if you’re a Performance person it’s quite likely nobody bothered to tell you when the systems were IPL’ed.
You might well know what the regime for starting and stopping CICS is but I... [More]

Over a year ago I wrote about a couple of iOS applications I was enjoying using. [1] And now it’s time to write about a third, as it’s part of my authoring toolkit.
In
Recent Conference Presentations I showed off my then new writing rig: Byword (with MultiMarkDown) and my iPad Mini with a Logitech light keyboard cover.
I said that would be my rig for a while. So this post also... [More]

h3, h4, p {
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} I’ve been meaning to write about MEMLIMIT and its importance for some time. [1] But it’s a moving target. So either there’s no good time to talk about it or lots of good times. So let me discuss it now and then again later as necessary. [2] So timing a post on MEMLIMIT is like choosing a wave to catch: In this case the... [More]

This post adds some additional DB2 Version 10 specifics to what I mentioned in
New zIIP Capacity Planning Presentation .
I said this would be a living presentation, and so it has proven to be.
It’s had two outings so far and there are a couple more confirmed. First the times I’ve given it: On 9 April 2014 I was very pleased this was the very first presentation given at the... [More]

There’s been some interest recently in whether a zBC12 as a standalone Coupling Facility would be a good idea. Having replied to one such question in email form I can count that as a draft for a blog post on the subject. It’s a complex question as are most about Parallel Sysplex configuration design. So this won’t be a comprehensive answer but I hope it’ll give you food for... [More]

I’m writing about intervals again. [1] Two things have occasioned this: I’ve been updating my code for DB2 Versions 10 and 11 [2] . I’ve dealt recently with customers with unhelpful SMF or RMF intervals. As I’ve said before it’s important to understand the provenance of the data you’re using.
This would be true whether it’s performance data, financial... [More]

As you know I mainly deal in SMF data (and other machine-generated instrumentation).
While I’m perfectly adept at conducting interviews and handling evidence from real live people there’s much merit in instrumentation. I’m also not keen on just replaying what you say back at you, with no value added in the process.
But I’m making an exception: I’ve just added to my... [More]

It’s only fair to warn you this gets technical straight away.
And is probably only interesting to a DB2 audience anyway.
And as someone who disclaims on his DB2 knowledge anyway you might not want to read this. Still with me?
Excellent! As described in Coping With DB2 Version 10 And Preparing For DB2 Version 11 I’ve been revamping my DB2 analysis code. [1] Here are a couple of areas... [More]

I’ve said this many times:
I’m not a DB2 person but I’ve bluffed my way in DB2 for many a year. [1] Perhaps that’s why I don’t get to use my DB2 analysis code nearly as much as I’d like. So it’s perhaps not so surprising my code fell behind when it came to new versions.
The last big update was for Version 8.
That was a big update - mainly because... [More]

The subtext of this post is “do try and keep up” - which is directed at me as much as anybody. And is a perpetual state of being when you’re dealing with evolving SMF data and enterprise computing environments. When I look at a system’s memory usage my code produces what I call a “PM2200” [1] chart. The giants on whose shoulders I balance precariously [2] first... [More]

As you might know I like maths, particularly algebra.
(If you’ve read
Another Neat Piece Of Algebra - Series Summation and
Hello, I’m Martin And I’m An Algebraic you do.) If there’s one thing I would be doing if I weren’t doing this [1] it might be teaching maths - but it would have to be at a level where algebra and calculus were substantial topics.
But I... [More]

In zIIP Address Space Instrumentation I discussed the subject of zIIP Capacity Planning. What I was working on - but wasn’t ready to reveal - was a presentation on zIIP Capacity Planning.
But I was also working on my new “zIIP CPU From Type 30” code.
And that’s indeed what that post is about. Now I am in a position to reveal my new presentation.
You can get it from here... [More]

Basic tutorial or advanced nicety? You decide... Having been told what I thought was a nice high level presentation was "a bit too technical" I'll confess to a perpetual (slight) anxiety about "level". Anyhow, this post is about inferences from LPAR names, particularly deactivated ones. (If you catch me saying "inactive LPARs" I apologise.
I mean ones that are defined on a machine but not... [More]

Increasingly people are going to want to understand their zIIP usage and do capacity planning for zIIPs.
Previously I’ve written about zIIP CPU numbers from the RMF perspective,
namely at the WLM Workload and Service Class levels.
This post is about taking it down a layer - to the address space level - using SMF Type 30 records. (I’ve always thought it a pity there isn’t a... [More]

Usually a residency ends on the last day. Well doesn’t everything? But this one’s been a little unusual in that regard.
Straight after the residency came a week in which two of us presented at the GSE UK Annual Conference on aspects of the residency: Dean Harrison presented on Scheduling and JCL aspects. I presented on Performance aspects. And Karen Wilkins, the other resident, was... [More]

This post is yet another spin off from the residency I'm on in Poughkeepsie. I mentioned in
We Have Residents! I might do something with JSON (Javascript Object Notation) and indeed I have. But why would a residency on Batch Performance concern itself with JSON (and indeed XML, which I've also written about in the Redbook)? The reason lies in the word "modernisation".
This actually works two... [More]

While working through a scenario in our residency it became (briefly) important to be able to preserve
sort order on a field.
But this field wasn’t sorted in any recognisable way.
So the records couldn’t be sorted alphabetically or numerically.
In fact they had to be sorted so that this field was preserved in the following sequence: red orange yellow green blue violet pink white... [More]

Actually it's not been quite that bad, jetlagwise. So on this third day we're moving into the creative phase.
For example I might be writing actual Redbook text, Karen might be writing actual COBOL, and Dean might be telling TWS to do his actual bidding. The past two days have been filled with kick off and getting stuff set up.
We did, though, sketch out an outline of the Redbook.
So that gives... [More]

If you’re looking for a considered opinion you came to the wrong place . Or so anyone reading
Down In The Dumps? shortly after reading
Enigma And Variations Of A Memory Kind might conclude. It’s possibly a fair cop, possibly not, but it got me thinking… In reality life is a sequence of experiences, many of which we hopefully learn something from.
But it’s a journey of... [More]

That’s such a horrible pun I must’ve used it before.
If so sorry (but not very). This post follows on from
Enigma And Variations Of A Memory Kind in a way.
In that post I mentioned DUMPSRV, in almost a throwaway fashion:
I happened to notice the memory usage in SMF 30 by DUMPSRV grew at just the point free memory took a dip. This post takes that idea and extends it a little - and... [More]

As I mentioned in
We Have Residents! we'll be working with a z/OS 2.1 system in October.
In fact I've already logged on to it.
I might even get to play with it before the residency starts, depending on current workload - but the priority is to hit the ground running by ensuring the environment is set up to our liking and that we have test data.
(And then there are those day-to-day... [More]

This post, unlike the previous one, is “on topic” for a Mainframe Performance Topics blog.
I hope nobody’s relying on that.
In fact I joke about renaming blog this to “Mainframe, Performance, Topics” the next time I ask for the header to be updated.
In fact I just might. I recently got some data from a customer that I thought showed a bug in my code. Instead it... [More]